The effect of confinement on thermally induced fluctuations in nanomagnets

TL;DR

This paper investigates how confinement affects thermally induced magnetization fluctuations in nanomagnets, revealing mode behaviors, temperature dependence, and energy barriers related to state switching.

Contribution

It provides a detailed analysis of internal magnon modes and their fluctuations in confined nanomagnets, including classification and energy barrier calculation.

Findings

Confinement influences magnon mode spatial extension.

Low frequency edge modes fluctuate between magnetic states.

Energy barriers for state switching are quantified.

Abstract

We study the magnetization dynamics in nanomagnets excited by stochastic magnetic fields to mimic temperature in a micromagnetic framework. The effect of confinement arising from the finite size of the structures is investigated, and we visualise the spatial extension of the internal magnon modes. Furthermore, we determine the temperature dependence of the magnon modes, and focus specifically on the low frequency edge modes, which are found to display fluctuations associated with switching between C- and S-states, thus posing an energy barrier. We classify this fluctuating behaviour in three different regimes, and calculate the associated energy barriers using the Arrhenius law.